Raising chairs are known; see the referenced U.S. Pat. Nos. 4,062,249 and 4,076,304, for example. A spring, or other similar device is provided in order to move the seat and/or backrest to follow the movement of a user, if the user wishes to rise from a seated to an erect position. The spring assists in lifting the user, and counteracts the weight of the user to help the user in rising from a seated to an erect position. The user, of course, must have a handle or other support on which the user can support her/himself upon rising, that is, brace her/himself. Such bracing also reduces the force necessarily exerted by the spring, or similar force-exerting structure, for example a counterweight, in order to reduce the force necessarily acting on the seat when the user changes from a seated to an erect position.
The German Patent Disclosure Document DE-OS No. 23 62 029 describes an adjustment arrangement to tilt the seat in a raising chair. The adjustment and force supply apparatus comprises two main gas springs, each attached to an end of the seat with one end portion and to a support frame with the other. The gas springs can be locked in an extended, or compressed position by locking elements which are controlled by hand levers and Bowden cables, similar to bicycle hand brake handles. The hand levers are attached to handle elements, which, again, may be similar to the end portions of bicycle handle bars, the handles being attached to the frame by suitable connecting elements, such as tubing.
In order to rise to an upright position with this raising chair, the user releases the locking of the main springs and perhaps also leans forward slightly. The user can hold onto two hand grips attached at the front to two vertical tubes extending across the seating surface and pull himself forward somewhat. The seat is pivoted upward, about its front edge, by the spring force and the user is brought to a standing position. In addition to the main springs, an auxiliary spring contributes to this pivoting movement. Now if the user wishes to return to the seated position from this standing position, he pivots a hand lever, which relaxes the auxiliary spring. The main springs are then compressed once again by the body weight of the user, so that the seat returns to the seating position, and once the proper lever grip has been released the seat is locked in this position. By pivoting an actuation lever forward, the user can prestress the auxiliary spring once again, thereby making its additional force available again for subsequently raising the user to an erect position.
This type of raising chair is relatively complicated and expensive to manufacture. A particular disadvantage is also that the hand grips are disposed at the front of the chair and thereby prevent the user from making a lateral transfer movement, such as may be desired, for instance, to shift to a toilet seat. Furthermore, the hand grip is in an unfavorable position during the erecting operation, so that with such a chair, the user can rise to a standing position only by exerting great force, if at all. For these reasons, a chair of this kind has not met with commercial success.